.NET下GDI＋的一些常用应用（水印，文字，圆角处理）

在某些情况下希望处理一些图片，比如

给图片添加一般文字：
原图

程序处理成


给图片添加水印：
原图

程序处理成


还有圆角效果：
原图

程序处理成


注：
（1）以下程序针对这个应用，也许这些对你没有用，但是基本的原理都差不多
（2）以上图为测试用，应该不算侵犯肖像权吧

程序界面：


程序点击这里下载。

如果需要提高图片质量，把
image.Save(sDstFilePath, ImageFormat.Jpeg);
改成

= ImageCodecInfo.GetImageEncoders()[0];
        myEncoder = Encoder.Quality;
        myEncoderParameters = new EncoderParameters(1);
        myEncoderParameter = new EncoderParameter(myEncoder, 100L); // 0-100
        myEncoderParameters.Param[0] = myEncoderParameter;
        image.Save(sDstFilePath, myImageCodecInfo, myEncoderParameters);
        myEncoderParameter.Dispose();
        myEncoderParameters.Dispose();

这是提高质量后的效果：


附一些关键代码：

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.IO;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;

public partial class Index : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            DirectoryInfo di = new DirectoryInfo(Server.MapPath(ConfigurationManager.AppSettings["uploadpath"]));
            this.lb_ImageList.DataSource = di.GetFiles("*.jpg");
            this.lb_ImageList.DataBind();
        }
    }
    protected void btn_upload_Click(object sender, EventArgs e)
    {
        string sFileName = this.FileUpload1.FileName;
        if (Path.GetExtension(sFileName).ToLower() != ".jpg")
        {
            ClientScriptManager csm = Page.ClientScript;
            csm.RegisterStartupScript(this.GetType(), "", "<script>alert('System can only handle jpg file!')</script>");
        }
        else
        {
            string sFileFullPath = Server.MapPath(ConfigurationManager.AppSettings["uploadpath"] + sFileName);
            this.FileUpload1.SaveAs(sFileFullPath);
            this.lb_ImageList.Items.Add(sFileName);
            this.lb_ImageList.SelectedIndex = -1;
            this.lb_ImageList.Items.FindByValue(sFileName).Selected = true;
            this.img_Src.ImageUrl = ConfigurationManager.AppSettings["uploadpath"] + sFileName;
        }
    }
    protected void lb_ImageList_SelectedIndexChanged(object sender, EventArgs e)
    {
        this.img_Src.ImageUrl = ConfigurationManager.AppSettings["uploadpath"] + this.lb_ImageList.SelectedValue; ;

    }
    protected void btn_Generate_Click(object sender, EventArgs e)
    {
        string sFileName = this.lb_ImageList.SelectedValue;
        string prefix = DateTime.Now.Minute.ToString() + DateTime.Now.Second.ToString();
        string sSrcFilePath = Server.MapPath(ConfigurationManager.AppSettings["uploadpath"] + sFileName);
        string sDstFilePath = Server.MapPath(ConfigurationManager.AppSettings["uploadpath"] + prefix + sFileName); ;
        if (this.rb_Text.Checked)
        {
            try
            {
                MyGDI.CreatePlainText(sSrcFilePath, sDstFilePath,this.tb_Text.Text,tb_Color.Text,tb_Size.Text,this.tb_Font.Text);
                this.lb_ImageList.Items.Add(prefix + sFileName);
                this.lb_ImageList.SelectedIndex = -1;
                this.lb_ImageList.Items.FindByValue(prefix + sFileName).Selected = true;
                this.img_Src.ImageUrl = ConfigurationManager.AppSettings["uploadpath"] + prefix+ sFileName;
            }
            catch (Exception ex)
            {
                Response.Write(ex.Message);
            }
        }
        else if (this.rb_Watermark.Checked)
        {
            try
            {
                MyGDI.CreateWatermark(sSrcFilePath, sDstFilePath, this.tb_Text1.Text, this.tb_Color1.Text, this.tb_Size1.Text, this.tb_Font1.Text, this.tb_Text2.Text, this.tb_Color2.Text, this.tb_Size2.Text, this.tb_Font2.Text, this.tb_bgcolor.Text, this.tb_transparence.Text);
                this.lb_ImageList.Items.Add(prefix + sFileName);
                this.lb_ImageList.SelectedIndex = -1;
                this.lb_ImageList.Items.FindByValue(prefix + sFileName).Selected = true;
                this.img_Src.ImageUrl = ConfigurationManager.AppSettings["uploadpath"] + prefix + sFileName;
            }
            catch (Exception ex)
            {
                Response.Write(ex.Message);
            }
        }
        else if (this.rb_Corner.Checked)
        {
            try
            {
                MyGDI.CreateRoundedCorner(sSrcFilePath, sDstFilePath, this.ddl_CornerLocation.SelectedValue);
                this.lb_ImageList.Items.Add(prefix + sFileName);
                this.lb_ImageList.SelectedIndex = -1;
                this.lb_ImageList.Items.FindByValue(prefix + sFileName).Selected = true;
                this.img_Src.ImageUrl = ConfigurationManager.AppSettings["uploadpath"] + prefix + sFileName;
            }          
            catch(Exception ex)
            {
                Response.Write(ex.Message);
            }
        }
    }
    protected void btn_Delete1_Click(object sender, EventArgs e)
    {
        string sFileFullPath = Server.MapPath(ConfigurationManager.AppSettings["uploadpath"] + this.lb_ImageList.SelectedValue);
        FileInfo fi = new FileInfo(sFileFullPath);
        fi.Delete();
        this.lb_ImageList.Items.Remove(this.lb_ImageList.SelectedItem);
    }
}

public class MyGDI
{
    public static void CreateWatermark(string sSrcFilePath, string sDstFilePath, string sText1, string sColor1, string sSize1, string sFont1, string sText2, string sColor2, string sSize2, string sFont2, string sBgColor, string sTransparence)
    {
        System.Drawing.Image image = System.Drawing.Image.FromFile(sSrcFilePath);
        Graphics g = Graphics.FromImage(image);
        g.SmoothingMode = SmoothingMode.AntiAlias;
        g.InterpolationMode = InterpolationMode.HighQualityBicubic;
        g.CompositingQuality = CompositingQuality.HighQuality;
        g.TextRenderingHint = System.Drawing.Text.TextRenderingHint.AntiAlias; //文字抗锯齿
        g.DrawImage(image, 0, 0, image.Width, image.Height);
        Font f1 = new Font(sFont1, float.Parse(sSize1));
        Font f2 = new Font(sFont2, float.Parse(sSize2));
        Brush brushfortext1 = new SolidBrush(ColorTranslator.FromHtml(sColor1));
        Brush brushfortext2 = new SolidBrush(ColorTranslator.FromHtml(sColor2));
        Brush brushforbg = new SolidBrush(Color.FromArgb(Convert.ToInt16(255 * float.Parse(sTransparence)), ColorTranslator.FromHtml(sBgColor)));
        g.RotateTransform(-20);
        Rectangle rect = new Rectangle(-image.Width/2-50, image.Height - 50, image.Width * 2, 40);
        g.DrawRectangle(new Pen(brushforbg), rect);
        g.FillRectangle(brushforbg, rect);
        Rectangle rectfortext1 = new Rectangle(-image.Width/2 + image.Width / 5, image.Height - 45, image.Width * 2, 60);
        for (int i = 0; i < 10; i++)
            g.DrawString(sText1, f1, brushfortext1, rectfortext1);
        Rectangle rectfortext2 = new Rectangle(-image.Width / 2 + image.Width / 5, image.Height -25, image.Width * 2, 60);
        for (int i = 0; i < 10; i++)
            g.DrawString(sText2, f2, brushfortext2, rectfortext2);
        image.Save(sDstFilePath, ImageFormat.Jpeg);
        image.Dispose();
      
    }

    public static void CreateRoundedCorner(string sSrcFilePath, string sDstFilePath, string sCornerLocation)
    {
        System.Drawing.Image image = System.Drawing.Image.FromFile(sSrcFilePath);
        Graphics g = Graphics.FromImage(image);
        g.SmoothingMode = SmoothingMode.HighQuality;
        g.InterpolationMode = InterpolationMode.HighQualityBicubic;
        g.CompositingQuality = CompositingQuality.HighQuality;
        Rectangle rect = new Rectangle(0, 0, image.Width, image.Height);
        GraphicsPath rectPath = CreateRoundRectanglePath(rect, image.Width / 10, sCornerLocation); //构建圆角外部路径
        Brush b = new SolidBrush(Color.White);//圆角背景白色
        g.DrawPath(new Pen(b), rectPath);
        g.FillPath(b, rectPath);
        g.Dispose();
        image.Save(sDstFilePath, ImageFormat.Jpeg);
        image.Dispose();
    }

    public static void CreatePlainText(string sSrcFilePath, string sDstFilePath,string sText, string sColor, string sSize, string sFont)
    {
        System.Drawing.Image image = System.Drawing.Image.FromFile(sSrcFilePath);
        Graphics g = Graphics.FromImage(image);
        g.SmoothingMode = SmoothingMode.AntiAlias;
        g.InterpolationMode = InterpolationMode.HighQualityBicubic;
        g.CompositingQuality = CompositingQuality.HighQuality;
        g.DrawImage(image, 0, 0, image.Width, image.Height);
        g.TextRenderingHint = System.Drawing.Text.TextRenderingHint.AntiAlias; //文字抗锯齿
        Font f = new Font(sFont,float.Parse(sSize));
        Brush b = new SolidBrush(ColorTranslator.FromHtml(sColor));
        Rectangle rect = new Rectangle(10, 5, image.Width, image.Height); //适当空开一段距离        
        for (int i = 0; i < 30; i++) //加强亮度
            g.DrawString(sText, f, b, rect);
        image.Save(sDstFilePath, ImageFormat.Jpeg);
        image.Dispose();
    }

    private static GraphicsPath CreateRoundRectanglePath(Rectangle rect, int radius, string sPosition)
    {
        GraphicsPath rectPath = new GraphicsPath();
        switch (sPosition)
        {
            case "TopLeft":
                {
                    rectPath.AddArc(rect.Left, rect.Top, radius * 2, radius * 2, 180, 90);
                    rectPath.AddLine(rect.Left, rect.Top, rect.Left, rect.Top + radius);
                    break;
                }

            case "TopRight":
                {
                    rectPath.AddArc(rect.Right - radius * 2, rect.Top, radius * 2, radius * 2, 270, 90);
                    rectPath.AddLine(rect.Right, rect.Top, rect.Right - radius, rect.Top);
                    break;
                }

            case "BottomLeft":
                {
                    rectPath.AddArc(rect.Left, rect.Bottom - radius * 2, radius * 2, radius * 2, 90, 90);
                    rectPath.AddLine(rect.Left, rect.Bottom - radius, rect.Left, rect.Bottom);
                    break;
                }

            case "BottomRight":
                {
                    rectPath.AddArc(rect.Right - radius * 2, rect.Bottom - radius * 2, radius * 2, radius * 2, 0, 90);
                    rectPath.AddLine(rect.Right - radius, rect.Bottom, rect.Right, rect.Bottom);
                    break;
                }
        }
        return rectPath;
    }
}